Synthetic materials with active contractions

In many biological systems, small things control mechanical properties at a much larger scale. In the cellular cytoskeleton, molecular motors control the mechanical response of the actin network. In the extracellular matrix, micrometric fibroblasts contract and relax to maintain nearly constant mechanical stresses over centimetric scales even when the matrix is stretched. In blood clots, aggregates of contractile platelets are responsible for the stiffening during coagulation. These phenonema are usually described within the framework of homogenization theories, identical to the one for composite materials. In particular, recent work showed that active mechanical dipoles were conserved over length scales, and that the dipole strength could be enhanced or reduced depending on material nonlinear properties, as well as in fibrous materials.

At the Institut Lumière Matière, we recently developped the first synthetic system that creates local reversible contractions inside a homogeneous material. It exploits the light-absorbing properties of micrometric particles and the phase-transition dynamics of a hydrogel. The goal of this project is twofold. Fully describe the phase-transition-triggered local contraction mechanism, and scale up this mechanism to create centimetric light-controllable hydrogels.

Funding category: Sans financement dédié
Candidature à déposer à l'école doctorale EDPHAST
PHD title: Doctorat de Physique
PHD Country: France